Stroke-shortening device for percussive tools.



C. O. HANSEN. STROKE SHORTENING DEVICE FOR PERCUSSIVBTOOLS.

APPLIOATION FILED MAY 31, 1912 1,056, 170.

Patented Man 18. 1913.

- piston 12 rotated b a unrrnn sra'ras r arianir orrrca.

CHARLES C. HANSEN, 0F EASTON, PENNSYLVANIA, ASSIGNOR. TO INGEBSOLL-RANDGQMPANY, OF NEW YORK. N. Y., A CORPORATION OF NEW JERSEY.

STROKE-SHORTENING DEVICE FOR PERGUSSIVE TOOLS.

To all whom it may concern:

Be it known that I, CHARLES C. HANSEN, a citizen of the l nited States,residing in Easton. in the county of Northampton and State ofPennsylvania, have invented certain new and useful Improvements inStroke-Shortening Devices for Percussive Tools, of which the followingis a specification.

This invention relates to percussive tools and more particularly to astroke shortening or cushioning device for such tools.

The object of this invention is to provide a simple and effective meansfor shortening the stroke of percussive tools, especially drills. underconditions which require short stroking such as in starting obliqueholes in rock faces and in drilling in soft rock.

lVith this object in view I have devised a mechanism a practicalembodiment of which is shown in the accompanying drawings in which l VFigure 1 is a. longitudinalsection through the drill embodying thedevice. Fig. 2 is a transverse section on the line 1IH of Fig. 1 and Ela side elevation showing the handle for operating the stroke shorteningmechanism.

' The device as shown is embodied in a rock drill of ordinaryconstruction which comprises a cylinder 1 in which reciprocates a &ritie bar 3. The valve iis of the balanced wing type one of its wingscontrolling the. inlet passages 5 and 6 leading respectively to the backand front end of the cylinder and the other of its wings controlling thecorresponding exhaust passages 7 and S. Operating fluid is admitted bythe inlet opening 9 and exhausts through the outlet 10, the valve beingthrown by compression in the inlet passages produced by the pistonatter'it has overrun the exhaust ports.

In the exhaust passage 7 is the stroke shortening valve which consistsof plate 11 so'shaped as to closely tit the passage 7 when turned in aposition transversely across the passage shown in Fig. -1. Through theplate is an perturelQ which is of small area in comparison to the sizeof the passage.

One edge of the plate 11 is provided with a.

cylindrlcal lu 13 seated for rotation in a depression in the face of thepassage while on theopposite edge or the plate 11 is a Specification ofLetters Patent.

Patented Mar. 18, 1913 Application filed May 31, 1912. Serial No.700,634.

shank it which rotates in bushing 15 threaded into the valve chestcasting. Secured to the outer end of the shank 14 is a handle 16provided with a rearwardly extended lug 17 in which slides a springpressed pin-18 adapted to be seated at will in either of thedepressions'lt) and 20. v

The operation of the device is evident from the description. When theplate 11 is in the position shown by the dotted lines in Fig. 1 thefluid from the back end of the cylinder will exhaust freely through thepassage 7 and outlet 10. lVhen however the plate 11 is in the positionshown by the full lines'ot Fig. 1 the fluid from the back end of thecylinder will exhaust only through the aperture 12 which will cushionthe hack stroke of the piston toa considerable extent thus causing thevalve to be thrown sooner and hence shortening the effective stroke ofthe piston.

Although the device as shown is applied to a rock drill it is adaptedfor use with any type of percussive tool. It is however particularlyadapted to valves of the type shown wherein the valve is thrown bypiston compression transmitted to the valve by the inlet passage.

l't is to be understood that'the device as shown and described disclosesonly one modification of the tool and-other changed and modified, formsare included within the spirit and scope of my invention as expressed inthe claims.

Tv'hat l: claim is: g

1. In a percussive tool, acylinder, a piston therein. a valve, an inletpassage controlled by said valve, a separate exhaust; passage controlledby-said valve and an apertured plate mounted for rotation in saidexhaust passage.

2. In a percussive tool. a cylinder a piston therein, a valve, an inletpassage controlled by said valve, a separate exhaust passage controlledby said valve. a plate ro tatahl-y mounted in said passage and tii 'ingsaid passage when transversely across it. an aperture in said plate, andmeans to rotate said plate' In a percussive tool, a cylinder, a pistontherein, a valve, an inlet passage controlled by said valve, a separateexhaust passage controlled by said valve so placed as to allow pistoncompression in said inlet pas-

